1. Field of the Invention
The present invention relates to condensation-crosslinking two-component dental molding materials based on polyethers, which are particularly suitable for taking impressions, as well as mixtures that can be obtained from them, and their use. Such materials are used in dental medicine, for example for taking tooth impressions, for bite registration, or for lining dental prostheses.
2. The Prior Art
Condensation-crosslinking dental molding materials usually contain hydroxyl-functional polymers with a silicon backbone, which crosslink and cure in the presence of water and metallorganic catalysts, for example organic tin or titanium compounds. However, such materials are comparatively hydrophobic, because of the silicon backbone of the polymers, so that significant proportions of surfactant must be added to them, for the purpose of reducing the surface tension and to adjust the required wettability.
As an alternative to this, two-component dental molding materials are known that contain polymers having terminal alkoxysilyl groups and a hydrophilic polyether backbone, which demonstrate sufficiently hydrophilic properties for wetting of the moist tooth substance. Usually, these materials consist of a base component containing alkoxysilyl-functional polyether having an average molecular weight of 800 to 20,000 g/mol, which can also have urea and/or urethane groups, as a function of their synthesis, fillers, as well as any other necessary additives, and a catalyst component that contains not only fillers and any other necessary additives but also an organic and/or inorganic acid as the catalyst.
Condensation-crosslinking two-component dental molding materials are described in European Patent No. EP 0 269 819 B1, the base component of which contains polyaddition products containing alkoxysilyl end groups, having a predominantly linear molecular structure and an average molecular weight of 800 to 20,000 g/mol, which have a content of polyether groups of 25 to 90 wt.-%, a content of urethane groups of 0.5 to 10 wt.-%, a content of urea groups of 0.5 to 10 wt.-%, as well as a content of terminal alkoxysilyl groups of 1 to 25 wt.-%, and the catalyst component of which contains a mixture containing water as well as organic and/or inorganic acids in weight amount ratios (water/acid) of 1:0.01 to 1:40.
European Patent No. EP 1 226 808 A2 discloses condensation-crosslinking two-component dental molding materials consisting of a base component and a catalyst component, the base component of which contains alkoxysilyl-functional polyethers having a linear or branched main chain and an average molecular weight of 800 to 20,000 g/mol, which have a content of polyether groups of 20 to 95 wt.-%, a content of terminal alkoxysilyl groups of 0.2 to 25 wt.-%, as well as a content of urethane groups or urea groups of up to 10 wt.-%, if necessary, and the catalyst component of which contains a mixture containing water as well as organic and/or inorganic acids in weight amount ratios of 1:0.01 to 1:40. Preferably, the catalyst component contains p-toluene sulfonic acid hydrate as the catalyst, as well as a polyether diol and additional additives, such as fillers, paraffin, emulsifier, and the like.
However, the known dental materials based on alkoxysilyl ethers have the disadvantage of binding with insufficient rapidity. Furthermore, the catalyst mixture, which according to the state of the art must necessarily contain an acid, is limited with regard to the chemical nature and the amount of fillers that can be added, so that special additives, such as emulsifiers and/or thickeners, must be added to it, so that the two components can be mixed using mixer systems that are usual on the market. Because of the lack of flexibility with regard to the addition of fillers, the components of the dental material must furthermore be specially formulated in order to obtain components to be mixed in a ratio of 1:1.